Alkylated naphthalenes as synthetic lubricant base stocks

ABSTRACT

This invention relates to alkylated methylnaphthalenes and their utility in lubricant base stocks. In particular, the alkylated methylnaphthalenes of the present invention have unexpectedly superior thermal and oxidative properties and may be used to improve the performance characteristics of other lubricant base oils.

This application is a continuation-in-part of U.S. Ser. No. 10/011,455 filed Nov. 29, 2001.

FIELD OF THE INVENTION

This invention relates to alkylated methylnaphthalenes and their utility in synthetic lubricant base stocks.

BACKGROUND OF THE INVENTION

Alkylaromatic fluids have been proposed for use as certain types of functional fluids where good thermal and oxidative properties are required. For example, U.S. Pat. No. 4,714,794 (Yoshida) describes monoalkylated naphthalenes as having excellent thermal and oxidative stability, low vapor pressure and flash point, good fluidity and high heat transfer capacity and other properties which render them suitable for use as thermal medium oils. The use of a mixture of monoalkylated and polyalkylated naphthalenes as a base for synthetic functional fluids is described in U.S. Pat. No. 4,604,491 (Dressler). Pellegrini U.S. Pat. Nos. 4,211,665 and 4,238,343 describe the use of alkylaromatics as transformer oils.

The alkylated naphthalenes are usually produced by the alkylation of naphthalene or a substituted naphthalene in the presence of an acidic alkylation catalyst such as a Friedel-Crafts catalyst, for example, an acidic clay as described in Yoshida U.S. Pat. No. 4,714,794 or Dressler U.S. Pat. No. 4,604,491 or a Lewis acid such as aluminum trichloride as described in Pellegrini U.S. Pat. Nos. 4,211,665 and 4,238,343. The use of a catalyst described as a collapsed silica-alumina zeolite for the alkylation of aromatics such as naphthalene is disclosed in Boucher, U.S. Pat. No. 4,570,027. The use of various zeolites including intermediate pore size zeolites such as ZSM-5 and large pore size zeolites such as zeolite L and ZSM-4 for the alkylation of various monocyclic aromatics such as benzene is disclosed in Young, U.S. Pat. No. 4,301,316.

In the formulation of functional fluids based on the alkyl naphthalenes, it has been stated that the preferred alkyl naphthalenes are the mono-substituted naphthalenes since they provide the best combination of properties in the finished product. The mono-substituted naphthalenes possess fewer benzylic hydrogens than the corresponding di-substituted or polysubstituted versions and were said to have better oxidative stability and therefore form better functional fluids and additives. In addition, the mono-substituted naphthalenes have a kinematic viscosity in the desirable range of about 5-8 cSt (at 100° C.) when working with alkyl substituents of about 14 to 18 carbon atoms chain length. Numerous work has been done to improve the selectivity to the desired monoalkylated naphthalenes:

U.S. Pat. No. 5,034,563, Ashjian et al., which is incorporated by reference, teaches use of a zeolite containing a bulky cation. The use of, e.g., USY with cations having a radius of at least about 2.5 Angstroms increases selectivity for desired mono-alkylated products. Suitable zeolites include those containing hydrated cations of metals of Group IA, divalent cations, especially of Group IIA, and cations of the Rare Earths.

U.S. Pat. No. 5,177,284, Le et al., which is incorporated by reference, discusses the desirable properties of alkylated naphthalene fluids with higher alpha:beta ratios, including improved thermal and oxidative stability. Le et al. generally describes the alkylation of naphthalene and substituted naphthalenes which may contain one or more short chain alkyl groups containing up to about 8 carbons, such as methyl or ethyl, and found that several parameters influenced the alpha:beta ratio of the alkylated naphthalene products, including steaming the zeolite, i.e., using steamed USY or steamed zeolite beta, lowering the alkylation temperature, or using an acid-treated clay. Lowering the alkylation temperature increases the alpha:beta ratio and results in an improvement in the alkylated naphthalene product qualities, including RBOT oxidation times.

U.S. Pat. No. 5,191,135 Dwyer et al., which is incorporated by reference, discloses the effect of co-feeding water for the alkylation reaction when using a large pore zeolite catalyst, such as zeolite Y. U.S. Pat. Nos. 5,191,134, and 5,457,254, incorporated by reference herein, disclose a similar alkylation process using MCM-41 and a mixed H/NH₄ catalyst, respectively.

As previously noted, the bulk of the prior art generally taught that mono-substituted naphthalene is the most desirable component for synthetic lubricant base stock with optimized thermal and oxidative stability and viscometrics. Accordingly, the prior art taught processes to improve selectivity and achieve the desired mono-alkylated products. Di-alkyl naphthalenes were thought to have inferior lubricant properties because di-alkylation inhibits the naphthalene rings to neutralize the oxygen, peroxides or radicals. Alkylated naphthalenes with di- or tri-alkyl components were thought to have poor thermal and oxidative stabilities.

JP 1996 302371, however, teaches that alkylated methyl naphthalene is also a good basestock candidate. Methyl naphthalene, preferably the 2-methyl naphthalene substituted with a long chain alkyl group wherein at least 35% of the substituted long chain alkyl groups are attached to the naphthalene at the 2 position of the long chain alkyl group has been found to possess RBOT oxidation times of 800 minutes and longer. Even alkylated methyl naphthalene wherein only 30% of the substituted long chain alkyl groups are attached to the naphthalene at the 2 position of the long chain alkyl group but synthesized using activated kaolin was reported as having a RBOT oxidation time of 420 minutes.

SUMMARY OF THE INVENTION

It has now been discovered that long chain alkyl substituted 1-methyl and/or 2-methylnaphthalenes, with 30% or less of the substituted long chain alkyl groups attached to the naphthalene at the 2 position of the long chain alkyl group have superior thermal and oxidative properties exceeding 500 minutes in the RBOT oxidation test, in many cases significantly better than mono-substituted naphthalenes.

Accordingly, the present invention extends the range of raw materials that can be used to produce synthetic base stock and establishes that long chain alkyl substituted 1-methyl and/or 2-methylnaphthalenes wherein 30% or less, preferably less than 30%, more preferably about 29% or less of the long chain alkyl groups are attached to the naphthalene at the 2 position of the long chain alkyl group have oxidative stability better than that of known alkyl naphthalene fluid or expected for such long chain alkyl group substituted methyl naphthalene fluids based on the teachings of the literature.

The present invention includes di-alkyl naphthalenes, having utility as synthetic lubricant base stocks, blending stocks, or as additives for other base stock fluids or liquid fuels. The present invention includes an alkylated naphthalene selected from the group consisting of a compound or mixture of compounds of the following formula (I):

wherein R¹ and R² are H, methyl;

-   -   R³ and R⁴ are an alkyl group having from about 6 to about 24         carbon atoms;     -   x is from 0 to about 2; and     -   y is from 0 to about 4;     -   with the proviso that at least one of R¹ and R² is other than H,         and at least one of x and y is other than 0, and wherein 30% or         less, preferably less than 30%, more preferably 29% or less of         the R³ and R⁴ group are attached to the naphthalene at the 2         position of the long chain alkyl group said long chain alkyl         substituted methyl naphthalene being prepared by the method         comprising reacting an alkylating agent with 1-methyl         naphthalene, 2-methylnaphthalene or a mixture of 1-methyl and         2-methyl naphthalene in a naphthalene to alkylating agent mole         ratio of at least about 2:1 at a temperature in the range of         about 150° C. to about 250° C., preferably about 150° C. to         about 225° C., more preferably about 175° C. to about 200° C.,         using USY zeolite as catalyst, preferably reacting 1-methyl         naphthalene or a mixture of 1-methyl and 2-methyl naphthalene         with an alkylating agent at a naphthalene to alkylating agent         rate of about 2:1 at a temperature of about 175° C. to about         200° C. over a USY zeolite catalyst or reacting an alkylating         agent with 2-methyl naphthalene in a naphthalene to alkylating         agent mole ratio of at least about 2:1 at a temperature in the         range of about 150° C. to about 225° C. using USY zeolite as         catalyst.

Preferably, R³ and R⁴ comprise alkyl groups having from about 8 to about 18 carbon atoms. Exemplary R³ and R⁴ groups include hexyl, heptyl, octyl, nonyl, iso-octyl, 2-ethyl hexyl, decyl, undecyl, dodecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl, each optionally having linear or branched alkyl groups.

The sum of x and y is preferably from about 1 to about 3. More preferably, the synthetic oils comprise di-alkyl naphthalenes wherein the sum of x and y is one, R¹ is H and R² is methyl.

The compounds of formula (I) have unexpectedly superior thermal and oxidative properties, especially when compared to mono-substituted naphthalenes or as would be expected for such alkyl methyl naphthalene materials based on the teaching in the literature. The alkylated 1-methyl or 2-methyl naphthalene compounds made as recited herein exhibit RBOT oxidation time of about 500 minutes or more, preferably about 600 minutes or more, more preferably about 700 minutes or more, most preferably between about 700 to 1300 minutes.

Another aspect of the present invention is directed to a method for improving the oxidative stability of lubricant compositions comprising adding a compound of formula (I) to a base oil.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, “alkylated methylnaphthalene” refers to a naphthalene compound that has a methyl group at the one or two position of the naphthalene ring and at least one additional alkyl group containing about 6 carbon atoms to about 24 attached at another position of the ring. In addition, all values set forth herein include all combinations and sub-combinations of ranges and specific values given therein.

The naphthalene starting material for the production of compounds of formula (I) comprises 1-methylnaphthalene, 2-methylnaphthalene or a substantially pure mixture of the two in any proportion. For example, 1- and 2-methylnaphthalenes are present in coke liquids or in the heavy fraction (greater than 10 carbon atoms) of aromatic reformate streams or the heavy bottom stream from a toluene disproportionation process or the heavy fraction from a catalytic cracking process, such as light cycle oil from an FCC process. Feed streams with higher 2-methylnaphthalene content, such as those from the highly selective toluene disproportionation process, are preferable because the alkylated 2-methylnaphthalene products generally have better oxidative stability and the alkylation process tends to be more efficient when compared to feedstreams containing higher amounts of 1-methylnaphthalenes. Additionally, the starting material may comprise a mixture of methylnaphthalene and naphthalene, but use of only 1-methyl or only 2-methyl or a substantially pure mixture of 1-methyl and 2-methyl naphthalene under the alkylation conditions recited herein insurer production of an alkylated methyl naphthalene product having a RBOT oxidation stability of about 500 minutes or more, preferably about 600 minutes or more, most preferably about 200 minutes or more, most preferably about 700 to 1300 minutes.

The alkylating agents which may be used to alkylate the 1-methyl and/or 2-methyl substituted naphthalenes include any aliphatic or aromatic organic compound having one or more available alkylating aliphatic groups capable of alkylating the substituted naphthalene. The alkylatable group itself should have at least about 6 carbon atoms, preferably at least about 8, and still more preferably at least about 12 carbon atoms. For the production of functional fluids and additives, the alkyl groups on the naphthalene preferably have from about 12 to about 24 carbon atoms, with particular preference to about 14 to 18 carbon atoms. A preferred class of alkylating agents are the olefins with the requisite number of carbon atoms, for example, the dodecenes, tetradecenes, pentadecenes, hexadecenes, heptadecenes, octadecenes, nonadecenes, and their branched analogs.

In preferred embodiments, the alkylating agent will be an olefin which may include internal olefins (such as 2- or 3-tetradecene), alpha (or 1-) olefins, vinylidene olefins (such as 2-methyl-1-tetradecene or 2,3,3-trimethyl-1-butene, or 2,4,4-trimethyl-1-pentene, or 2,4,4-trimethyl-2-pentenes). The alpha olefins and linear internal olefins are most readily available. The alkylating agent employed should be one having the lowest probability of resulting in more than 30% of the long chain alkyl group being attached to the naphthalene at the 2 position of the long chain alkyl group despite the use of zeolite USY which has itself been found to result in 30% or less, preferably less than 30%, more preferably 29% or less of the long chain alkyl groups being attached to the naphthalene at the 2 position of the long chain alkyl group.

Mixtures of olefins, for example, mixtures of C₁₂-C₂₀ or C₁₄-C₁₈ olefins, may also be used in the present invention. Branched alkylating agents, especially oligomerized olefins such as the trimers, tetramers, or pentamers of light olefins such as ethylene, propylene, and butylenes are also useful. Other useful alkylating agents which may be used, include alcohols such as hexadecanols, heptadecanols, octadecanols, nonadecanols, dodecanols and doundecanols. Alkyl halides such as hexadecyl chlorides, octadecyl chlorides, dodecanyl chlorides, and higher homologs may also be used in the present invention.

The alkylation reaction between the substituted naphthalene and the alkylating agent is carried out in the presence of an ultra stable Y (USY) zeolite alkylation catalyst.

When USY contains hydrated cations, it catalyzes the alkylation in good yields with excellent selectivity. Zeolite USY is a material of commerce, available in large quantities as a catalyst for the cracking of petroleum. It is produced by the stabilization of zeolite Y by a procedure of repeated ammonium exchange and controlled steaming. Processes for the production of zeolite USY are described in U.S. Pat. No. 3,402,966 (McDaniel), U.S. Pat. No. 3,923,192 (Maher) and U.S. Pat. No. 3,449,070 (McDaniel); see also Wojciechowski, Catalytic Cracking, Catalysts, Chemistry and Kinetics, Chemical Industries, vol. 25, Marcel Dekker, New York, 1986, ISBN 0-8247-7503-8, to which reference is made for a description of zeolite USY, its preparation and properties. Zeolite USY prepared in accordance with the teaching of U.S. Pat. Nos. 5,177,284 and 5,034,563 both of which are incorporated herein by reference is the preferred form of Zeolite USY to produce the desired results.

Zeolite USY according to U.S. Pat. Nos. 5,034,563 and 5,177,284 is a porous crystalline zeolite containing cations having a radius of at least 2.50 Å, preferably at least about 3.0 Å. It may also be characterized as having a minimum pore dimension of at least 7.4 Å, and an alpha value of between about 0.1 alpha to about 1000 alpha, preferably an alpha value of less than about 300 alpha, more preferably ranging from about 5 alpha to about 250 alpha.

The zeolite USY catalyst may be composited with a matrix material or binder which is resistant to the temperatures and other conditions employed in the alkylation process. Such materials include active and inactive materials and synthetic or naturally occurring zeolites as well as inorganic materials such as clays, silica or silica-alumina. The latter may be either naturally occurring or in the form of gelatinous precipitates or gel including mixtures of silica and metal oxides. Use of an active material in conjunction with the zeolite may change the conversion and/or selectivity of the catalyst. Inactive materials suitably serve as diluents to control the amount of conversion so that alkylation products can be obtained economically without employing other means for controlling the rate of reaction. Binders which may be incorporated to improve the crush strength and other physical properties of the catalyst under commercial alkylation operating conditions include, but are not limited to, naturally occurring clays, e.g., bentonite and kaolin, as well as silica, alumina, zirconia and mixtures thereof.

The alpha value of the zeolite is an approximate indication of the catalytic cracking activity of the catalyst compared to a standard catalyst. The alpha test gives the relative rate constant (rate of normal hexane conversion per volume of catalyst per unit time) of the test catalyst relative to the standard catalyst which is taken as an alpha of 1 (Rate Constant=0.016 sec −1). The alpha test in described in U.S. Pat. No. 3,354,078 and in J. Catalysis, 4,527 (1965); 6,278 (1966); and 61,395 (1980), to which reference is made for a description of the test.

Zeolite USY has a high initial alpha value of up to about 1000.

The stability of the alkylation catalyst may be increased by steaming. U.S. Pat. Nos. 4,663,492; 4,594,146; 4,522,929; and 4,429,176 are incorporated by reference herein, and describe conditions for the steam stabilization of zeolite catalysts which can be utilized to steam-stabilize the catalyst.

The alkylation process of this invention is conducted such that the organic reactants, e.g., the alkylatable methylnaphthalene compound and the alkylating agent, are brought into contact with the catalyst in a suitable reaction zone such as, for example, in a flow reactor containing a fixed bed of the catalyst composition, under effective alkylation conditions.

The alkylation reaction conditions employed in the present invention to produce long chain alkylated methyl naphthalene having 30% or less, preferably less than 30%, more preferably 29% or less of the long chain alkyl groups attached to the methyl naphthalene at the 2 position of the long chain alkyl group and exhibiting RBOT oxidation lines of about 500 minutes, or longer, preferably about 600 minutes or longer, more preferably about 700 minutes or longer, most preferably about 700-1300 minutes comprising reacting the alkylating agent and the 1-methyl-naphthalene, 2-methyl naphthalene or substantially pure mixture of 1-methyl- and 2-methyl-naphthalene at a naphthalene to alkylating agent mole rate of at least about 2:1, preferably about 2:1 to 10:1, more preferably about 2:1 to 4:1, most preferably about 2:1 at a temperature of between about 150° C. to about 250° C., preferably about 150° C. to 225° C., more preferably about 175° C. to 200° C. in the presence of a USY zeolite catalyst, preferably reacting 1-methyl naphthalene or substantially pure mixture of 1-methyl naphthalene and 2-methyl naphthalene with an alkylating agent at a naphthalene to alkylating agent ratio of at least about 2:1, preferably about 2:1 to 10:1, more preferably about 2:1 to 4:1, most preferably about 2:1 at a temperature of about 175° C. to about 200° C. in the presence of a USY zeolite catalyst, or reacting the alkylating agent with the 2-methyl naphthalene at a naphthalene to alkylating agent mole ratio of at least about 2:1, preferably about 2:1 to about 10:1, more preferably about 2:1 to 4:1, most preferably about 2:1 at a temperature between about 150° C. to about 225° C., preferably about 150° C. to about 200° C., more preferably about 175° C. to about 200° C. in the presence of a USY zeolite catalyst.

Typical reaction pressures include a pressure from about 0.1 to about 100 atmospheres, preferably from about 1 to about 30 atmospheres. The required pressure may be maintained by inert gas pressurization, preferably with nitrogen.

Typical reaction times are from about. 0.5 to about 100 hours, preferably from about 2 to about 72 hours, more preferably about 4 to 24 hours. The reaction time is dependent on temperature and the amount of catalyst used in the process. Generally, higher reaction temperatures and a higher catalyst charge promotes faster reaction rates.

Generally, the amount of catalyst charged is about 0.1 wt % to about 10 wt % in a slurry reactor. A low catalyst charge may cause longer reaction times and a high catalyst charge may be uneconomical to run, causing filter plugging during the catalyst removal step. Preferably, the catalyst charge is about 0.5 wt % to about 5 wt %. The reaction may be carried out in a fixed-bed continuous operation where the catalyst is in pellet or extruded form and packed in a tubular reactor heated to the desirable temperature. The feed is introduced at a specific weight hourly space velocity (WHSV) ranging from about 0.1 to about 20, preferably from about 0.5 to about 5, more preferably about 0.2 to about 4 to achieve a high conversion.

The reactants can be in either the vapor phase or the liquid phase and can be neat, i.e., free from intentional admixture or dilution with other material(s), or they can be brought into contact with the catalyst composition with the aid of carrier gases or diluents such as, for example, hydrogen or nitrogen. The alkylation can be carried out as a batch-type reaction typically employing a closed, pressurized, stirred reactor with an inert gas blanketing system or in a semi-continuous or continuous operation utilizing a fixed or moving bed catalyst system.

In preparing compounds of formula (I), an amount of dimer of the alkylating olefin will be co-produced. The alkylated methyl naphthalenes herein comprising formula (I) will typically contain <1 wt % dimer whether used as a basestock or as a co-basestock.

They may be separated from the reaction mixture by stripping off unreacted alkylating agent and recovering the formula (I) compound in the conventional manner. It has also been found that the stability of the alkylated product may be improved by filtration over activated charcoal and by alkali treatment to remove impurities, especially acidic byproducts formed by oxidation during the course of the reaction. The alkali treatment is preferably carried out by filtration over a solid alkali material, preferably calcium carbonate (lime).

Generally, feedstock high in 2-methylnaphthalenes are more preferred because they may be more reactive than 1-methylnaphthalenes and the 2-methylnaphthalene alkylation product has better oxidation stability than 1-methylnaphthalene alkylation products. As noted previously, the heavy bottom stream from highly shape-selective toluene disproportionation processes are typically high in 2-methylnaphthalenes and especially suitable for use in the present invention.

The compounds of formula (I) may be used to improve the oxidative stability of lubricants. For example, the oxidation stability of the compounds of formula (I) as measured under the Rotating Bomb Oxidation Test (RBOT) (ASTM D2272) is generally greater than about 500 minutes, preferably greater than about 600 minutes, more preferably greater than about 700 minutes. In preferred embodiments, the RBOT values are from about 700 to 1300 minutes. All values set forth herein include all combinations and subcombinations of ranges and specific values given therein.

In addition, the kinematic viscosity of the compounds of formula (I) at 100° C. is from about 2 to about 30 cS, more preferably from about 3 to about 20 cS, with viscosity index (VI) values from about 50 to about 180, preferably greater than 60. The pour point of the compounds of formula (I) is from about 0 to about −60° C., more preferably from −10 to about −55° C. All values set forth herein include all combinations and sub-combinations of ranges and specific values given therein.

The long chain alkylated methyl naphthalene base oils comprising compounds of formula (I) may be used by themselves as the basestock for synthetic lubricant formulations. They can also be used as a co-base stock with other synthetic basestocks, such as polyalphaolefins (PAO), polyalkyleneglycol (PAG), polybutene (PIB), alkylbenzene (AB), or with conventional mineral oils, such as 100 to 800 SUS SN oils from catalytic or conventional dewaxed processes. The base oils comprising compounds of formula (I) may also be used with hydrocracked or hydroisomerized basestocks such as UCBO from Chevron, BP hydrocracked stocks, slack wax-isomerized basestocks or Fischer-Tropsch wax-isomerized basestocks (collectively, these fluids are referred to as Group II and Group III basestocks). The above basestocks typically have RBOT of ≦about 150.

Generally, when used as a co-basestock, the alkylated methyl naphthalene comprises from about 2 to about 90 wt % of the total lubricant basestock, and preferably greater than about 5 wt % of the total lubricant basestock. The use of the alkylated methyl naphthalene significantly improves the finished lubricant's thermal, oxidative, and hydrolytic stability as well as lubricant additive solvency, sludge dispersancy and antiwear or extreme-pressure metal surface protection.

As noted above and indicated in the following examples, compounds of formula (I) have superior oxidative stabilities and viscometrics when compared to mono-alkylated naphthalenes. Accordingly, the synthetic base oils of the present invention may be substantially devoid of mono-alkylated naphthalenes and still provide excellent lubricating properties.

The present alkylated methyl naphthalenes may be incorporated with conventionally used additives for lubricating oils such as an antioxidant, detergent dispersant, viscosity index improver, pour point depressant, oiliness improver, anti-wear agent, extreme pressure agent, friction modifying additive, anti-corrosive agent, metal inactivating agent, anti-rust agent, seal compatibility improver, anti-foaming agent, emulsifier, demulsifier, bactericide, or colorant.

The present alkylated methyl naphthalenes may be used to lubricate surfaces of various structures and elements that require lubrication. As used herein, “surface” refers to the outer part of structures or particles. The compounds of formula (I) may be used in various functional fluid formulations such as crank case lubricant, two cycle engine oil, hydraulic lubricant, drilling lubricant, turbine oil, grease, gear oil, transmission oil, and paper machine oil.

The following examples are illustrative and not meant to be limitations.

EXAMPLES

The general procedure described herein was used to collect the following data and is specifically described for Example 2 of Table 1. In this experiment, 1-methylnaphthalene (1-MN), 142 gram (1 mole) and 12.5 gram USY catalyst prepared as described in U.S. Pat. Nos. 5,177,284 and 5,034,563 were premixed in a 500 ml round bottom flask and the complete reaction system was purged with N₂ to eliminate air. The reaction flask was heated to 200° C. under nitrogen atmosphere. 1-hexadecene, 112 gram (0.5 mole), was added slowly into this mixture in two hours. The reaction mixture was reacted for three more hours and then cooled down to room temperature. Analysis of the reaction mixture by gas chromatography was used to determine the amounts of unreacted reactants and showed that most of the C₁₆ olefin was converted into product. The product, i.e., the lube product, was isolated by filtering off the solid catalyst and distilled at 120° C./<1 millitorr vacuum for more than one hour to remove any unreacted olefin and methylnaphthalene (MN).

The resulting product was analyzed and product properties are summarized below. Oxidation stability was analyzed under the Rotating Bomb Oxidation Test (RBOT) and the B-10 oxidation test. The RBOT test protocol is described in ASTM D2272.

The B-10 oxidation test is used to evaluate mineral oil and synthetic lubricants either with or without additives. The evaluation is based on the resistance of the lubricant to oxidation by air under specified conditions as measured by the formation of sludge, the corrosion of a lead specimen, and changes in neutralization number and viscosity. In this method, the sample is placed in a glass oxidation cell together with iron, copper and aluminum catalysts and a weighed lead corrosion specimen. The cell and its contents are placed in a bath maintained at a specified temperature and a measured volume of dried air is bubbled through the sample for the duration of the test. The cell is removed from the bath and the catalyst assembly is removed from the cell. The oil is examined for the presence of sludge, the total acid number (TAN) (ASTM 664), and Kinematic Viscosity (Kv) increase at 100° C. (ASTM D445). The lead specimen is cleaned and weighed to determine the loss in weight.

Other properties to be measured include Bromine No. (ASTM D1159), VI, and Pour Point (ASTM D97).

The following examples illustrate the excellent thermal and oxidative stabilities of the compounds of formula (I) as well as the effect of several variables on the properties and yield of the compounds, i.e., lube products.

The data in Table 1 demonstrates the effect of MN/olefin molar ratios on the lube product (a methylnaphthalene acts as the starting material and an olefin acts as the alkylating agent for purposes of the examples herein). Examples 1 to 3 show that increasing 1-MN/olefin molar ratios from 1/1 to 4/1 improves the oxidative stability of the lube product as measured by RBOT (the RBOT time increases from 145 minutes to 805 minutes). A similar trend was observed for 2-MN/olefin molar ratios (Examples 4 and 5). Varying the MN/olefin ratios do not appear to change product viscosities, VI, and pour points and conversion of olefins were very high (>90%) at all MN/olefin ratios. A MN/olefin molar ratio of at least about 2:1 is needed to produce an alkylated product exhibiting a RBOT of 500 minutes or greater. TABLE 1 Effect of MN/Olefin Molar Ratio Example No. 1 2 3 4 5 Feed, MN 1-MN 1-MN 1-MN 2-MN 2-MN Olefin C16 1-C16 C16 1-C16 1-C16 Mole Ratio MN/O 1/1 2/1 4/1 1.0/1 2.0/1 Catalyst Type USY USY USY USY USY Catalyst Wt % 5 5 5 5 5 Rxn Temp, ° C. 200 200 200 200 200 Rxn Time, Hours 18 4 4 9 18 % total conversion. 94.5 71.3 58.0 95.3 77.9 % 1-C16 conversion 94.2 95.9 98.5 95.7 97.7 Product Selectivity mono-C16-MN 95.6 94.1 99.6 96.1 99.7 di-C16-MN 4.4 2.8 0.4 3.9 0.3 others 0.0 3.1 0.0 0.0 0.0 Product Properties Kv @ 100° C., cS 5.7 5.6 5.8 5.5 5.3 Kv @ 40° C., cS 41.4 41.0 40.9 38.4 36.8 VI 67 62 76 67 64 Pour Point, ° C. −47 −46 −46 −48 −49 Bromine Number 0.27 0.5 0.45 0.02 0.03 Oxidative Stability RBOT, minutes 145 703 805 239 744 B10 Test at 163° C./40 hours % Kv Increase 21.8 6.5 0.0 12.0 10.2 TAN Incr., mg KOH 1.87 1.6 0.35 0.9 1.1 Sludge nil nil trace light trace wt % lead loss 19.5 7.2 2.6 10.1 8.6

The data in Table 2 demonstrates the effect of reaction temperature on lube yields and properties from 1-MN or 2-MN at a 2/1 MN/olefin mole ratio. Examples 6 to 8 show that increasing reaction temperature from 175° C. to 225° C. increases 1-hexadecene conversion from 74% to 100%, but this has no effect on viscosities, VI and pour points. At lower reaction temperatures, such as 175° C. and 200° C. (Examples 6 and 7), the lube products have longer RBOT time than the product produced at 225° C. (Example 8, 168 minutes). Similar trends were observed for lube products from 2-MN (Examples 9 to 12). For example, by running the reaction at a lower reaction temperature, such as 150 and 175° C. (Examples 9 and 10), lube products with RBOT time of >1000 minutes were obtained. It is seen that for the alkylation of 1-MN a maximum temperature of about 200° C. is required if the product is to have a RBOT of 500 minutes or greater while for the alkylation of 2-MN the temperature can range from 150 to 225° C. and the product has a RBOT of 500 minutes or greater. TABLE 2 Effect of Reaction Temperature on Lube Yields and Properties from 1-MN and 2-MN Example No. 6 7 8 9 10 11 12 Feed, MN 1-MN 1-MN 1-MN 2-MN 2-MN 2-MN 2-MN Olefin C16 1-C16 C16 C16 C16 1-C16 C16 Mole ratio MN/O 2/1 2/1 2/1 2/1 2/1 2/1 2/1 Catalyst Type USY USY USY USY USY USY USY Catalst Wt % 5 5 5 5 5 5 5 Rxn Temp, ° C. 175 200 225 150 175 200 225 Rxn Time, hours 8 4 3 72 8 4 2 % Total Conv. 49.2 71.3 79.8 63.9 67.3 70.8 69.7 % 1-C16 Conv. 73.8 95.9 99.9 75.8 92.6 98.7 94.3 Product Selectivity Mono-C16-MN 98.6 94.1 99.2 98.1 100.0 98.0 99.0 di-C16-MN 1.4 2.8 0.8 1.9 0.0 1.2 1.0 Others 0.0 3.1 0.0 0.0 0.0 0.8 0.0 Product Properties Kv @ 100° C., Cs 5.5 5.6 5.6 5.3 5.3 5.3 5.3 Kv @ 40° C., cS 37.8 41.0 40.6 35.4 36.4 36.2 37.2 VI 72 62 62 73 68 64 59 Pour Point, ° C. −43 −46 −46 −45 −49 −48 −49 Bromine No. 0.48 0.5 0.28 0.19 0.14 0 0.1 Oxidative Stability RBOT, min 737 703 168 1111 1280 847 600 B10 Test at 163° C./40 hours % Kv Increase 0 6.5 13.8 7.2 6.5 9.2 9.9 TAN Increase, 0.4 1.6 2.05 0.5 0.49 1.2 1.63 mg KOH Sludge trace nil trace trace trace trace trace wt % lead loss 12.67 7.2 14.396 7.0 6.59 8.1 9.0

The data in Table 3 demonstrates the effect of different olefins, different MN sources and different catalysts on lube yields and properties.

Examples 13 to 15 showed that 1-tetradecene, 1-hexadecene and 1-octadecene may be used as the alkylating reagent. By changing the olefin feeds, lube products of 4.6 to 6.1 cS were obtained. All of the products possessed very long RBOT times (from 744 minutes to 1000 minutes).

Examples 16 to 18 illustrate the results obtained when using different sources of methylnaphthalenes or a mixture of naphthalene and methylnaphthalenes. Suresol-187 used in Ex. 16 and 17 is a commercial product available from Koch Chemical Co. and contains 52% 2-MN and 45% 1-MN. Example 18 used a feed containing equal weight of naphthalene, 1-MN and 2-MN. The products of examples 16 to 18 were produced in high yields but had RBOT times which were markedly inferior to those of the products produced by the alkylation of 1-methyl naphthalene or 2-methyl naphthalene individually.

Example 19 and 20 demonstrate that using a MCM-22 catalyst, instead of a USY catalyst, produced lube products with RBOT time lower than that of products produced using zeolite USY catalyst. TABLE 3 Effect of Different olefins, different MN sources and different catalysts on lube yields and properties. Different Olefins Different MN Source Different Catalyst Example No. 13 14 15 16 17 18 19 20 Feed, 2-MN 2-MN 2-MN Suresol- Suresol- N, 1-MN 2-MN MN 187 187 1-2-MN Olefin C14 1-C16 C18 1-C16 1-C13 C16 1-C16 1-C16 Mole 2/1 2.0/1 2/1 2.0/1 2.0/1 2/1 2.0/1 2.0/1 Ratio MN/O Catalyst USY USY USY USY USY USY MCM22/ MCM22/ Type Al₂O₃ Al₂O₃ Catalyst 5 5 5 5 5 5 5 5 Wt % Rxn 200 200 200 200 200 200 200 200 Temp, ° C. Rxn 4 18 4 4 5 4 18 18 Time, hours % Total 76.0 77.9 80.5 71.5 68.6 90.5 59.3 75.1 Conv. % 99.4 97.7 99.5 98.7 99.7 90.8 89.3 98.1 1-C16 Conv. Product Selectivity Mono-C16 99.2 99.7 98.4 96.8 99.1 92.0 88.4 81.4 di-C16- 0.8 0.3 1.6 1.8 0.9 8.0 11.4 18.5 MN Others 0.0 0.0 0.0 1.4 0.0 0.0 0.2 0.1 Product Properties Kv @ 4.6 5.3 6.1 5.5 4.7 5.3 6.7 6.5 100° C., cS Kv @ 30.8 36.8 43.3 38.1 32.0 35.5 53.0 51.1 40° C., cS VI 29 64 81 66 33 73 71 64 Pour −46 −49 −26 −47 −48 −48 −45 −47 Point, ° C. Bromine 0.08 0.03 0.12 0 0 0.21 0.62 0 No. Oxidative Stability RBOT, 1000 744 817 216 170 191 121 525 min B10 Test at 163° C./40 hours % Kv 8.6 10.2 9.7 20.5 21.7 24.4 7.3 5.8 increase TAN 0.77 1.1 0.74 2.6 1.7 1.26 0.94 0.9 Incr., mg KOH Sludge trace trace trace light trace trace nil trace wt % lead 8.056 8.6 8.904 16.5 15.8 13.911 8.4 3.7 loss

Table 4 compares the properties of lubes made from 1-MN or 2-MN versus a commercial mono-alkylated naphthalene lube available from Mobil Chemical Co. (produced according to the method disclosed in U.S. Pat. No. 5,034,563). The data demonstrates that MN-based lube products have better oxidative stability as measured by the RBOT times. TABLE 4 Comparison of Lube properties Made from MN vs. from Naphthalene Alkyl Naphthalene Example Number From Mobil 7 11 20 Chem Feed, MN 1-MN 2-MN 2-MN Unalkylated Naphthalene Olefin 1-C16 1-C16 1-C16 1-C16 Product USY USY MCM 22/Al₂O₃ USY Properties Kv @ 100° C., Cs 5.6 5.3 6.5 4.8 Kv @ 40° C., cS 41.0 36.2 51.1 27 VI 62 64 64 76 Pour Point, ° C. −46 −48 −47 −43 Bromine No. 0.5 0 0 0.2 Oxidative Stability RBOT, min 703 847 525 150 Oxidative Stability % Kv Increase 6.5 9.2 5.8 7.6 TAN Incr., 1.6 1.2 0.9 0.7 mg KOH Sludge nil trace trace Trace wt % lead loss 7.2 8.1 3.7 9.9

Example 21 is an analysis of a representative sample of alkylated methyl naphthalene in regard to the degree of long chain alkyl group substitution through the secondary carbon atom of a 1-methyl long chain alkyl group.

The long chain alkyl substituted methyl naphthalene used in the present invention differs from that of JP 1996302371A. The long chain alkyl substituted methyl naphthalene used in the present invention contains about 30% or less of the long chain alkyl groups attached to the naphthalene at the 2 position of the long chain alkyl group whereas JP 1996302371A alkyl methyl naphthalene has at least 35% of the long chain alkyl groups attached to the naphthalene at the 2 position of the long chain alkyl groups.

In a typical run, using USY catalyst at 200° C. at a ratio of MN to alkylating agent of 2:1, the product had 29% of the long chain alkyl groups attached to the naphthalene at the 2 position of the long chain alkyl groups, and a high amount (about 55%) of the long chain alkyl groups attached to the naphthalene at the 4 or higher position of the long chain alkyl groups. A low amount of attachment of the long chain alkyl group to the naphthalene at the 2 position of the long chain alkyl groups is important for consistent good product properties.

In the present invention all alkylated methyl naphthalene products were produced from either 1-methyl naphthalene or 2-methyl naphthalene and have pour points of −26° C. or less, the vast majority (19 out of 20 samples) having pour points of less than −40° C. In a comparable run using a catalyst other than USY and reaction conditions to produce a product high in long chain alkyl group attachment to the naphthalene at the 2 position of the long chain alkyl group, the product has a higher pour point (−23° C.). The data are summarized below. TABLE 5 Example 1 Comparative Example % alkyl substitutent type of C16 chain at the 2 position 29 62 at the 3 position 16 20 at the 4+ position 55 18 Kv @ 100° C., cS 4.9 5.82 Pour point, ° C. −40 −23

Although the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the scope and spirit of the present invention. 

1. An alkylated methyl naphthalene having a RBOT of at least about 500 minutes said alkylated methyl naphthalene made by the method comprising reacting an alkylating agent having at least 6 carbon atoms with 1-methyl naphthalene, 2-methyl naphthalene or a substantially pure mixture of 1-methyl naphthalene and 2-methyl naphthalene in a methyl naphthalene to alkylating agent ratio of at least about 2:1 at a temperature in the range of about 150° C. to about 250° C., a pressure of about 0.1 to 100 atmosphere for from about 0.5 to about 100 hours over a USY zeolite, said alkylated methyl naphthalene having about 30% or less of the long chain alkyl groups attached to the naphthalene at the 2 position of the long chain alkyl group.
 2. The alkylated methyl naphthalene of claim 1 having a RBOT of at least about 500 minutes said alkylated naphthalene made by the method comprising reacting an alkylating agent having at least 6 carbon atoms with 1 methyl naphthalene in a methyl naphthalene to alkylating agent ratio of at least about 2:1 at a temperature in the range of about 175° C. to about 200° C. a pressure of about 0.1 to 100 atmospheres for from 0.5 to about 100 hours over a USY zeolite, said alkylated methyl naphthalene having about 30% or less of the long chain alkyl group attached to the naphthalene at the 2 position of the long chain alkyl group.
 3. The alkylated methyl naphthalene of claim 1 having a RBOT of at least about 500 minutes, said alkylated methyl naphthalene made by the method comprising reacting an alkylating agent having at least 6 carbon atoms with 2-methyl naphthalene in a methyl naphthalene to alkylating agent ratio of at least about 2:1 at a temperature in the range of about 150° C. to about 225° C., a pressure of about 0.1 to 100 atmospheres for from about 0.5 to about 100 hours over a USY zeolite catalyst said alkylated methyl naphthalene having about 30% or less of the long chain alkyl group attached to the naphthalene at the 2 position of the long chain alkyl group.
 4. The alkylated methyl naphthalene of claim 1 having a RBOT of at least about 500 minutes said alkylated methyl naphthalene made by the method comprising reacting an alkylating agent having at least 6 carbon atoms with a substantially pure mixture of 1 methyl naphthalene and 2 methyl naphthalene in a methyl naphthalene to alkylating agent ratio of at least about 2:1 a temperature in the range of about 175° C. to about 200° C., a pressure of about 0.1 to 100 atmosphere for from about 0.5 to about 100 hours over a USY zeolite catalyst said alkylated naphthalene having about 30% or less of the long chain alkyl groups attached to the naphthalene at the 2 position of the long chain alkyl group.
 5. The alkylated naphthalene of claim 1, 2, 3 or 4 having a RBOT of about 600 minutes or longer.
 6. The alkylated naphthalene of claim 1, 2, 3 or 4 having a RBOT of about 700 minutes or longer.
 7. The alkylated naphthalene of claim 1, 2, 3 or 4 having a RBOT of about 700 to 1300 minutes or longer.
 8. The alkylated naphthalene of claim 1, 2, 3 or 4 wherein the ratio of methyl naphthalene to alkylating agent is about 2:1 to about 10:1.
 9. The alkylated naphthalene of claim 1, 2, 3 or 4 wherein the ratio of methyl naphthalene to alkylating agent is about 2:1 to about 4:1.
 10. The alkylated naphthalene of claim 3 wherein the temperature of reaction is about 150° C. to 200° C.
 11. The alkylated naphthalene of claim 3 wherein the temperature of reaction is about 175° C. to 200° C.
 12. The alkylated naphthalene of claim 1, 2, 3 or 4 wherein the alkylated methyl naphthalene has less than about 30% of the long chain alkyl groups attached to the naphthalene at the 2 position of the long chain alkyl group.
 13. The alkylated methyl naphthalene of claim 1, 2, 3 or 4 wherein the alkylated methyl naphthalene has 29% or less of the long chain alkyl groups attached to the naphthalene at the 2 position of the long chain alkyl group. 